Determination of radium isotopes in environmental samples by gamma spectrometry, liquid scintillation counting and alpha spectrometry: a review of analytical methodology.

Radium (Ra) isotopes are important from the viewpoints of radiation protection and environmental protection. Their high toxicity has stimulated the continuing interest in methodology research for determination of Ra isotopes in various media. In this paper, the three most routinely used analytical techniques for Ra isotope determination in biological and environmental samples, i.e. low-background γ-spectrometry, liquid scintillation counting and α-spectrometry, were reviewed, with emphasis on new methodological developments in sample preparation, preconcentration, separation, purification, source preparation and measurement techniques. The accuracy, selectivity, traceability, applicability and minimum detectable activity (MDA) of the three techniques were discussed. It was concluded that the MDA (0.1mBqL(-1)) of the α-spectrometry technique coupled with chemical separation is about two orders of magnitude lower than that of low-background HPGe γ-spectrometry and LSC techniques. Therefore, when maximum sensitivity is required, the α-spectrometry technique remains the first choice.